Contemporary art in wellbore related applications utilize a diversely structured hollow tubular string, which extends from one end at the earth's surface to an opposite end at or near the bottom of a wellbore where a cutting bit and related equipment (sometimes and herein referred to synonymously as “drilling utensil”) is attached to the tubular string. Said drilling utensils are used to bore through rock to extend the hole to a desired depth and location. Fluids utilized typically include water, oil, “mud”, acids and/or gas such as air, nitrogen or natural gas. Such fluids are pumped down the interior of the string, through the bit, cooling the bit, washing drilled rock cuttings from the bit face and lifting those rock cuttings tip to the surface where they are removed from the fluid. If the tubular string is jointed, then the downhole bit can be rotated from the surface. If the tubular string is either jointed or continuous, the downhole bit can be rotated utilizing a downhole hydraulic/pneumatic, positive displacement/turbine, or electric motor that is installed just above the bit to turn the bit without turning the tubular drill string. As the bit cuts and the circulated fluid moves the cuttings away from the bit/drilling utensil tip and up the wellbore to the surface, the bit and tubing string are lowered so that the bit maintains contact with the bottom of the hole that continues the drilling process. The above procedures are also utilized to clean out and re-enter existing wellbores or plugged wellbores.
In drilling operations utilizing downhole motors of the contemporary art, circulating fluid (liquids and/or gas) is pumped into the interior of a hollow tubular string, down the tubular string directly into the motor section (void between the motor housing and shaft where the resides the motor's stator and rotor elements), through the motor section powering the motor, transitioning from the outside of the internal rotating shaft into the shaft at the end of the motor section, into a bit flow channel inside the bit, then exiting through the end of the bit/drilling utensil. The exiting fluid then cleans and removes the rock cuttings generated by this process from the bit/utensil face and lifts them past the motor housing and up the hole to the surface. Minimum flow rate and pressure requirements of the circulating fluid necessary to efficiently clean and lift rock cuttings to the surface are well known to those skilled in the art. Should minimum flow rate not be achieved and maintained, the drilling process will be impaired or bound—sometimes with the tubular string and drilling equipment becoming stuck in the well. It is important to note that the fluid type, flow rate and pressure requirements of a given motor may significantly vary from the hydraulic flow requirements to clean the wellbore. Consequently, allowance for additional fluid volumes are often required to bypass the motor section and, when required, high pressure fluids of known volumes and pressures should be delivered to/near the tool/bit tip directly. Such fluid “by-pass” capability through the motor to the lead bit/drilling utensil, however, is not available to the industry via technology of the contemporary art.
Recent improvements have been made in the drilling of oil and gas, environmental and service wells and pipeline and utility boreholes, especially in the ability to direct, guide and control drilling operation in non-vertical directions, allowing a bottom-hole location to be offset from the surface (hole) location. Indeed, today, a well's bottom-hole location can be miles distant from its corresponding surface location. To do this with contemporary downhole motors, a bent sub (short piece of the tubular string with a fixed bend in it) is placed above the motor encouraging or causing the cutting bit to change axial direction. Contemporary art requires more than 60 feet of generally vertical distance to transcend the drilling operations from a vertical to a horizontal orientation, with the industry aggressively striving to shorten this curve length. Some of the barriers to shorten this curve length are the motors' length, diameter and torque capabilities. The derived benefits from such curved or bent drilling operations are to maximize the length of the hole within the zone of interest, to lessen rig time and costs, and to minimize costly potential well problems.
Downhole motors used in drilling applications are typically hydraulic and/or (more recently) pneumatic powered, positive displacement motors. Widely recognized hydraulic and pneumatic motors are of the Moineau and roller vane types. Electric and turbine powered motors can also be used for downhole operations, but are not widely practiced within the contemporary art. Motors that require clean power fluids are typically not used currently in the industry as well. Air (pneumatic) hammers and bits are rarely used below such downhole motors although the benefits of such have been recognized. Hydraulic hammers are being developed currently.
In all known motor designs of the contemporary art, the motor housing is affixed to the tubular string (extended from the surface, hereafter also called the “base”) and is therefore non-rotating relative to the base/tubing string; the internal shaft is rotated relative to the housing and base by the motor (with stator and rotor situated between the fixed housing and rotating shaft); and the drilling utensil is directly attached to the downhole end of the shaft which extends out of the motor housing and is thusly rotated. All known such contemporary motors have flow rate, pressure and speed limitations (both minimum and maximum) that must be met to ensure proper motor operation.
As stated earlier, all liquids, gases and solids utilized in this process of the contemporary art must go through the motor section to get to the drilling utensil for bit and bearing cooling and bit cleaning. While some fluids can be vented into the drilled hole (void outside of the drill string and tools) before the motor section and, therefore, not get to the bit or motor, the reverse option (i.e. more fluid getting to the bit than going through the motor) is not possible. This fact requires the maximum flow rate of a chosen motor must sufficiently cool and clean the tools, bit and hole drilled in the well.
The most common Moineau type downhole motors used for drilling purposes typically fall between a minimum 6 to over 30 feet in length; are relatively inflexible; are limited by temperature and pressure due to the utilized rubber elements; are sensitive to the hydraulic power fluid utilized (i.e. no acids and few solvents) due to the nibber elements; and are limited by minimum and maximum flow rates of the power fluid. Such limitations restrict the use of Moineau motors for highly deviated/directional/curved drilled holes; for pumping acids, bases, solvents and other corrosive fluids; for high pressure and temperature applications; and for high flow rate applications. These motor requirements and limitations are well known to those skilled in the practice of the art. Another limitation is the design and maintenance of pressure seals between a rotating and a fixed surface in these rugged conditions, especially at higher pressures.
Furthermore, it has been well documented in the oil and gas, environmental, pipeline, utility and water jetting industries that rocks, cements and other natural and manmade materials can be efficiently drilled, cut and/or fragmented at an enhanced rate utilizing high pressure, high velocity fluids. Drilling rate improvements using this technique are directly related to the material's destructibility/compressive strength, fluid density and compressibility, fluid flow rate and applied pressures. Typically a “threshold” pressure of the material must be exceeded before any benefit of this technique can be realized. However, no method is available utilizing technology of the contemporary art to efficiently transmitted high pressure fluids through the contemporary motor section to be delivered at the drill utensil/bit tip as it is rotating.
Another well-documented method in the oil and gas, environmental, pipeline, utility and water jetting industries to enhance the drilling and cutting process of many materials is “abrasive jetting”. This process utilizes the addition of solids (sands, fine ground rock, metal spheres) to a high pressure, high velocity carrying fluid to enhance the cutting process. Again, no mechanism in the contemporary art has been developed to allow use of this advanced drilling technique without the full high-pressure fluid/solid stream passing through the internal motor section(s).
Contemporary downhole hydraulic motors can only be put in positional series, increasing power (torque and horsepower) with the flow path of the power fluid only in series, i.e. with power fluid exiting one motor then entering as the high pressure into the next motor/motor stage. In this configuration, all motors/motor stages in series turn in the same shaft in the same direction and at the same rotational speed. Thus no motor can work independently of the others. Also, no current design of downhole motors allows power fluid to fully bypass the motor section to obtain higher rates or high-pressured (greater than 5,000 psig) hydraulic fluid at the utensil/tool/bit tip for other uses, such as running other motors in series, hydraulic and abrasive jetting ahead of the bit. Consequently, high pressure hydraulic jetting, abrasive jetting and the bypassing of fluids to the bit tip or other drilling utensils and flexibility in operating motors in series are all needs of downhole drilling motors that are not available via the contemporary art.
Furthermore, no instrumentation can be installed below the motor section, i.e. between the motor and bit, that has hydraulic or electrical communication through the motor section in the contemporary art. This is due to the disruption of the hydraulic flow path by the motor and the rotating shaft/bit. This limitation forces all such instrumentation to be above the motor and therefore 30 to 90 feet above/behind the lead bit or drilling utensil. Such near-bit instrumentation is important to maintain heading and direction, dip, measure pressure, rock types and fluid types in the just drilled rock. Sensing this information as near the bit as possible is important for efficient drilling operations.
The same limitations listed immediately above can be said about electrical motors below the initial motor section with limitations on getting the power/communication past the top motor to the subsequent, lower electrical motors. Electric motors for downhole drilling use are not utilized in contemporary art due to limitations on cooling of the motor components and getting fluid flow to the bit/drilling utensil for cooling, lubrication and bit/hole cleaning. By resolving these problems with electric motors, such motors may be utilized more frequently.
Additionally, drill rates with conventional methods can be limited by the torque limits of the tubular string and connections. This limit dictates the size, grade of the materials and the connection type used for the drill string. By limiting the torque transmitted from the drilling process to the drilling string above the motor(s), lower grade materials, connection types and string diameters may be used. There are no means to provide such balancing or reduction of the transmitted torque using conventional techniques, without reduced drilling effectiveness of the drilling process.
Enlargement of existing holes is common within the pipeline, utility and oil and gas industries. The need to drill an enlarged hole, greater than an uphole restriction that the bit/motor must pass through, is becoming more important as the industry pushes for smaller hole sizes and fewer casing string. If the hole above the desired drill point is larger than the desired hole size, conventional methods can be used. These include making additional ‘trips’ to take off the smaller bit and install the larger, desired bit. If the pipe is jointed and rotated from the surface, a larger ‘reaming’ bit behind the smaller lead bit can be used for concurrent drilling and reaming. With either jointed or continuous drill pipe, contemporary bi-centered bits can be used to drill a larger hole than the bit has passed through uphole. This one-pass hole enlargement using a singular bi-centered bit can be done with contemporary downhole motors or with rotation from the surface. Contemporary downhole motors cannot utilize separate and independent bits to concurrently drill and ream a given hole in a single pass—absent the use of a bi-centered bit.
Lastly, new advanced techniques to improve the drilling process are being developed using laser and or plasma energies applied to the materials to be ‘drilled’ or removed just ahead of the bit/drill utensil. The problem of such processes include getting power from the laser/plasma tool to ahead of the bit and/or through the motor section(s) and in keeping the wellbore hole clean of “drilled” materials. No current method exists to use a downhole motor and/or vibrator immediately above/behind the “bit” with these new processes to breakup the just cooled and solidified displaced drilled materials. No current method exists to apply a cooling fluid directly ahead of the bit/drilling utensil tip, after thermal spalling/melting/vaporizing, to cool and re-solidify the “drilled” materials for break-up and removal out of the wellbore. In addition, any method that allows cooling and breakup of these displaced “drilled” materials will further advance these and similar processes.
A hydraulic motor(s) was proposed in referenced U.S. Pat. No. 5,518,379, by Harris and Sussman, that claimed central passage of pressured fluids through a rotating “tubular rotor having an interior motive fluid flow channel . . . extending along the length of the rotor”. Quite distinguishable from the instant invention, the ‘379’ patent requires dual motors in series and utilizes the interior flow channel only for operations of these motors. The only claim made of the internal shaft channel was to allow the operation of the hydraulic motors in series. It is important to note that the ‘379’ motor designs and all motor designs found of the contemporary art, the center shaft rotates relative to the base. Since it is difficult to have sturdy high-pressure (5000 psi and higher) seal connections across the rotating shaft-non-rotating base junction, operating pressures must be restricted. Within material limits, the higher the available, effective pressure differential pressure across a motor section the higher the torque output that would be available. Thus, if higher pressures can be utilized across the motor section, for the same torque rating the motor can be shorter in length. Higher pressures within and through the motor to the drill utensils are also limited by these motor seal designs and capabilities.
Increasing temperatures also reduce the available useable pressure, due to reduced materials' strengths. Most contemporary downhole motors are limited to about 315 degrees Fahrenheit due to required material selections. The industry is constantly pushing to drill deeper where temperatures can exceed 400 degree Fahrenheit, well beyond the capabilities of all but a few motors. Thus with lower seal requirements and proper selection of materials, higher operating temperatures can be allowed. An all stainless steel or equivalent metal motor would have the ultimate temperature potential.
The industry(s) is also pushing new power fluids that are lighter, heavier or non-damaging to the drilled formation(s). Such special fluids can also be used to help cleanout old or re-entered wells, pipes and pipelines of scale, paraffin, cements or other solids. These new fluids include nitrogen, carbon dioxide (liquid and/or gas), solvents, acids (acetic, hydrochloric, formic) and bases. Most contemporary motors, except special designs of the ‘379’ motor, cannot utilize the full range of fluids that the industry has available for use. A downhole motor that can utilize the full range of these fluids as a power fluid, through internal design or materials selection (in particular an all metal design), can gain a wider acceptance and use in the industry.
Consequently, to remedy deficiencies associated with downhole motors of the contemporary art, there exists the following needs that serve as objects of the instant invention and to which the instant invention addresses itself:
One object of the instant invention is the need for a downhole motor that can deliver high torque in a short length to allow drilling highly deviated/directional/curved holes.
Yet another object of the instant invention is a downhole motor that is insensitive to fluid types due to an all-metal, or selective material design.
An additional object of the instant invention is a downhole motor that can operate at higher pressures (differential and/or internal operating) and temperatures.
Another object of the instant invention is a downhole motor that allows for all or a portion of the fluid flow to bypass the motor section for bit/motor/bearing/rock cooling, bit cleaning, wellbore hole cleaning, near-bit instrumentation monitoring and powering of near-bit motors in series, vibrators, sonic devices and other devices in lower positional series to an upper/top/first motor.
Another object of the instant invention is a downhole motor that allows for electrical lines/wires to go through a motor section(s) for near-bit instrumentation sensing monitoring and powering of nearer-bit electrical motors in series, electrical vibrators, sonic devices and other electrical devices in lower positional series to an upper/top/first motor.
A further object of the instant invention is a downhole motor that will allow for high pressure fluids to be transmitted through the motor and utilized at the drilling utensil/bit tip for hydraulic jetting, abrasive jetting and/or for operating motors in series.
An additional object of the instant invention is to provide an integration of motor housing and tool functions that can shorten the overall length of the drilling assembly.
A next object is the ability to drill a larger hole than the size bit selected or drill a larger hole than the bit/motor earlier past through (i.e. through an up hole restriction).
Another object is the ability to allow lower drill string requirements, including lower torque and strength capabilities, and smaller pipe diameters.
Lastly, an object of the instant invention is to allow pressurized fluid flow to cool but not contaminate an electric motor suitable for drilling applications and to provide cuttings cleaning at the bit tip and in the wellbore while utilizing such an electric motor.
It is intended to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated herein by reference, and which constitute a part of this specification, illustrate certain embodiments of the invention and, together with the detailed description, serve to explain the principles of the present invention.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in this application to the details of construction and to the arrangement so the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.
Further, the purpose of the foregoing abstract is to enable the U.S. Patent and Trademark Office and the public generally, and especially the design engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. The abstract is neither intended to define the invention of the application, which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.
Additional objects and advantages of the invention are set forth, in part, in the description which follows and, in part, will be apparent to one of ordinary skill in the art from the description and/or from the practice of the invention.
These together with other objects of the invention, along with the various features of novelty which characterize the invention, are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference would be had to the accompanying drawings, depictions and descriptive matter in which there is illustrated preferred embodiments and results of the invention.